In pouch or bag-shaped beverage containers having a membrane seal which is to be pierced by a straw, there is a problem making the seal sufficiently easy for the consumer to pierce. The piercing of the membrane seal may especially be a problem for small children who frequently utilize such containers and who lack the dexterity of adults.
The beverage pouches which are currently being marketed are fabricated from a laminated sheet material which is built up as follows from the outside to the inside: polyester film/printing ink/coating adhesive/metal foil/coating adhesive/heat-sealable plastic (e.g., polyethylene) film. Such a laminate is further described in U.S. Pat. No. 5,425,583 which is hereby incorporated by reference.
In the present commercial pouches, the outer polyester foil is removed within a straw piercing area so that the straw (typically a pointed straw) does not have to pierce the polyester film. Typically the straw piercing area is in the shape of a circle having a diameter in excess of the diameter of the straw. The straw piercing area has usually been removed from the polyester film before this film is laminated or adhered to the metal foil. To gain access to the pouch the straw must then only pierce the metal foil and adhered polyethylene film; however, this has still proven to be a difficult task.
Aforementioned U.S. Pat. No. 5,425,583 discloses an improved straw piercing opening wherein a hole is punched through all layers of the pouch laminate and a sealing film is affixed to the inner side of the polyethylene film around the straw piercing opening. Although this approach facilitates entry of the straw into the pouch, the added material and operational cost associated with this approach are not desirable.